The semiconductor industry continues to improve the integration density of various electronic components (e.g., transistors, diodes, resistors, capacitors, etc.) by continual reductions in minimum feature size. This allows more components to be integrated into a given area. In some applications, these smaller electronic components also require smaller packages that utilize less area than conventional packages.
Three dimensional integrated circuits (3DICs) are a recent development in semiconductor packaging in which multiple semiconductor dies are stacked upon one another, such as package-on-package (PoP) and system-in-package (SiP) packaging techniques. Some 3DICs are prepared by placing dies over dies on a semiconductor wafer level. The 3DICs have, for example, decreased length of interconnects between the stacked dies, and thus provide improved integration density and other advantages, such as faster speeds and higher bandwidth. However, there are many challenges related to 3DICs.